title: Effects of Endotoxin and Psychological Stress on Redox Physiology, Immunity and Feather Corticosterone in Greenfinches.
abstract: Assessment of costs accompanying activation of immune system and related neuroendocrine pathways is essential for understanding the selective forces operating on these systems. Here we attempted to detect such costs in terms of disruption to redox balance and interference between different immune system components in captive wild-caught greenfinches (Carduelis chloris). Study birds were subjected to an endotoxin-induced inflammatory challenge and temporary exposure to a psychological stressor (an image of a predator) in a 2*2 factorial experiment. Injection of bacterial endotoxin resulted in up-regulation of two markers of antioxidant protection - erythrocyte glutathione, and plasma oxygen radical absorbance (OXY). These findings suggest that inflammatory responses alter redox homeostasis. However, no effect on markers of oxidative damage to proteins or DNA in erythrocytes could be detected. We found no evidence that the endotoxin injection interfered with antibody production against Brucella abortus antigen or the intensity of chronic coccidiosis. The hypothesis of within-immune system trade-offs as a cost of immunity was thus not supported in our model system. We showed for the first time that administration of endotoxin can reduce the level of corticosterone deposited into feathers. This finding suggests a down-regulation of the corticosterone secretion cascade due to an endotoxin-induced immune response, a phenomenon that has not been reported previously. Exposure to the predator image did not affect any of the measured physiological parameters.
authors.affiliation: Department of Zoology, Institute of Ecology and Earth Sciences, Tartu University, Tartu, Estonia.
authors.forename: Richard
authors.initials: R
authors.lastname: Meitern
authors.forename: Elin
authors.initials: E
authors.lastname: Sild
authors.forename: Mari-Ann
authors.initials: MA
authors.lastname: Lind
authors.forename: Marju
authors.initials: M
authors.lastname: Männiste
authors.forename: Tuul
authors.initials: T
authors.lastname: Sepp
authors.forename: Ulvi
authors.initials: U
authors.lastname: Karu
authors.forename: Peeter
authors.initials: P
authors.lastname: Hõrak
mesh_terms: D000818:Animals; D000917:Antibody Formation; D000975:Antioxidants / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D002003:Brucella abortus / Q000276:immunology; D003048:Coccidiosis / Q000473:pathology / Q000662:veterinary; D003345:Corticosterone / Q000032:analysis* / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D004731:Endotoxins / Q000633:toxicity*; D005241:Feathers / Q000378:metabolism*; D046369:Finches / Q000276:immunology / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D050050:Protein Carbonylation / Q000187:drug effects; D011863:Radioimmunoassay; D017382:Reactive Oxygen Species / Q000097:blood; D013315:Stress, Psychological; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000975:Antioxidants; D004731:Endotoxins; D017382:Reactive Oxygen Species; D005978:Glutathione; D003345:Corticosterone